1. Field of the invention
The present invention concerns methods for assembling the constitutive elements of an antenna reflector, and more particularly, methods for securing these elements with respect to one another.
2. Description of the prior art
Antenna reflectors generally comprise a fixed carrier structure having a predetermined shape, upon which is placed a metallic mirror, the mirror forming a surface for reflecting waves.
The mirror is generally constituted by a material known as an air transparent material, i.e. a material which has very little wind resistance and which is generally produced in the form of a grid plate or expanded metal. Its form determines the radiation characteristic of the antenna; this is the reason why it must be shaped very accurately. The carrier structure is formed of metal sheets conventionally known as "combs" or "ribs", these metal sheets corresponding in shape to the rear section of the mirror. They can either be assembled together n order to form a resistant framework or be secured in position by another resistant framework formed of brackets or grating that supports the whole.
The methods for assembling the elements of the carrier structure such as the metal plates supporting the mirror generally comprise performing a riveting or a screwing or soldering in order to secure.these metal plates with respect to one another. The assembling method of the mirror upon this structure conventionally comprises performing a riveting and using flat cover-plates or in using spring staples or also in welding the mirror onto the structure.
The main drawback of these methods results from the fact that pressures are exerted on the elements and especially upon the mirror when the staples or the rivets are placed in position. These pressures provoke deformations of the mirror which modify the radiation characteristics of the antenna. When the elements are assembled by welding, the thermal stresses exerted during the welding operation will cause undesirable deformations of the mirror.